Molecular dynamics simulations are performed to investigate the water permeation across the single-walled carbon nanotube with the radial breathing mode (RBM) vibration. It is found that the RBM can play a significant role in breaking the hydrogen bonds of the water chain, accordingly increasing the net flux dramatically, and reducing drastically the average number of water molecules inside the tube with the frequency ranging from 5000 to 11 000 GHz, while far away from this frequency region the transport properties of water molecules are almost unaffected by the RBM. This phenomenon can be understood as the resonant response of the water molecule chain to the RBM. Our findings are expected to be helpful for the design of high-flux nanochannels and the understanding of biological activities, especially the water channelling.

By assuming that only gravitation exists between dark matter (DM) and normal matter (NM), we study the effects of fermionic DM on the properties of neutron stars using the two-fluid Tolman-Oppenheimer-Volkoff formalism. It is found that the mass-radius relationship of the DM admixed neutron stars (DANSs) depends sensitively on the mass of DM candidates, the amount of DM, and interactions among DM candidates. The existence of DM in DANSs results in a spread of mass-radius relationships that cannot be interpreted with a unique equilibrium sequence. In some cases, the DM distribution can surpass the NM distribution to form DM halo. In particular, it is favorable to form an explicit DM halo, provided the repulsion of DM exists. It is interesting to find that the difference in particle number density distributions in DANSs and consequently in star radii caused by various density dependencies of nuclear symmetry energy tends to disappear as long as the repulsion of accumulated DM is sufficient. These phenomena indicate that the admixture of DM in neutron stars can significantly affect the astrophysical extraction of nuclear equation of state by virtue of neutron star measurements. In addition, the effect of the DM admixture on the star maximum mass is also investigated.Comment: to be published in Phys. Rev. C (2014

No abstract

No abstract

Within a density-dependent relativistic mean-field model using in-medium meson-hadron coupling constants and meson masses, we explore effects of in-medium hyperon interactions on properties of neutron stars. It is found that the hyperonic constituents in large-mass neutron stars can not be simply ruled out, while the recently measured mass of the millisecond pulsar J1614-2230 can constrain significantly the in-medium hyperon interactions. Moreover, effects of nuclear symmetry energy on hyperonization in neutron stars are also discussed.Subject headings: dense matter -equation of state -stars: neutron

Effects of the density dependence of the nuclear symmetry energy on ground-state properties of superheavy nuclei are studied in the relativistic mean-field theory. It is found that the softening of the symmetry energy plays an important role in the empirical shift [Phys. Rev. C 67, 024309 (2003)] of spherical orbitals in superheavy nuclei. The calculation based on the relativistic mean-field models NL3 and FSUGold supports the double shell closure in 292 120 with the softening of the symmetry energy. In addition, the significant effect of the density dependence of the symmetry energy on the neutron skin thickness in superheavy nuclei is investigated.

At present, neutron star radii from both observations and model predictions remain very uncertain. Whereas different models can predict a wide range of neutron star radii, it is not possible for most models to predict radii that are smaller than about 10 km, thus if such small radii are established in the future they will be very difficult to reconcile with model estimates. By invoking a new term in the equation of state that enhances the energy density, but leaves the pressure unchanged we simulate the current uncertainty in the neutron star radii. This new term can be possibly due to the exchange of the weakly interacting light U-boson with appropriate in-medium parameters, which does not compromise the success of the conventional nuclear models. The validity of this new scheme will be tested eventually by more precise measurements of neutron star radii. 14.70.Pw, 97.60.Jd Neutron star (NS) is a unique place to test fundamental forces at the extremes of matter density, gravity and magnetic fields. Unfortunately, uncertainties in both the Equation of State (EOS) of super-dense nuclear matter and the strong-field gravity strongly interplay with each other in determining observational properties of neutron stars, for the latest review, see, e.g., [1]. For instance, in a simple version of modified gravity where the non-Newtonian gravity exists, neutron stars could have very different structures compared to predictions using Einstein's General Relativity (GR) theory of gravity [2][3][4]. The radius of a neutron star is one of the most important observables sensitive to the underlying nuclear EOS and gravity theories used. Currently, within GR the radius of a canonical NS has been predicted to be roughly from 11 to 15 km [5-9] depending on the EOS used. Provided the third family of compact stars known as strange stars exist, their radii could be as small as 7 or 8 km [10][11][12], although these models normally predict star masses much smaller than the masses of observed massive neutron stars. Thus, the measurement of NS radii plays a very important role in resolving several issues in fundamental physics. Unfortunately, the extraction of NS radii from observations still suffers from large systematic uncertainties [13] involved in the distance measurements and theoretical analyses of the light spectrum [6,[14][15][16]. Consequently, a wide range of the radius with the mass around 1.4 M ⊙ has been reported [16][17][18][19][20][21][22][23][24]. In particular, using the thermal spectra from quiescent low-mass X-ray binaries (qLMXBs) Guillot and collaborators extracted NS radii of R NS = 9.4 ± 1.2 km [24]. Another recent comprehensive study of spectroscopic radius measurements suggest that for a 1.5 M ⊙ NS the extracted * Electronic address: wzjiang@seu.edu.cn † Electronic address: bao-an.li@tamuc.edu ‡ Electronic address: ffattoye@indiana.edu radii are 10.8 +0.5 −0.4 km [25]. It is important to note that at the moment no consensus has been reached yet on the extracted NS radii. For instance, Bogdanov found a 3-σ lowe...

We have studied the evolution and dilepton production of a chemically equilibrating quark-gluon system at finite baryon density. We found that due to the increase of the quark phase lifetime with increasing initial quark chemical potential and other factors, such as, higher initial temperature, larger gluon density, and gluon fusion or quark annihilation cross section, thermal charmed quarks provide a dominant contribution to the dilepton yield. This results in a significant enhancement of intermediate mass dilepton production.